This invention relates to fluid-operated, reciprocating pumps, and especially to double-diaphragm-type pumps that utilize a reversing valve to control the reciprocating, pumping action. More particularly, the invention relates to simplification of the construction of such pumps, to the operation of a pilot valve for controlling the reversing valve, and to the provision of a capability for operating such pumps with their intake and exhaust manifolds at either a high level or a low level position.
Fluid-operated pumps, such as diaphragm pumps, are widely used particularly for pumping liquids, solutions, viscous materials, and slurries or suspensions. The word "liquid" as used herein is intended to include all such materials. Typical diaphragm pumps of this general type are shown in my earlier U.S. patents listed below:
______________________________________ 3,304,126 3,782,863 3,514,227 3,814,548 3,741,689 3,860,034 3,741,692 ______________________________________
Other double-diaphragm pumps are shown in the patents listed below:
______________________________________ 2,625,886 3,652,187 2,679,209 3,791,768 2,780,177 3,838,946 3,192,865 4,019,838 3,338,171 4,123,204 3,548,716 4,172,698 ______________________________________
Double-diaphragm pumps of the type disclosed in the above-listed prior art patents are well known for their utility in pumping thickened or solids-laden liquids, as well as for pumping plain water, other liquids, and low-viscosity solutions based on such liquids. Accordingly, double-diaphragm pumps have found extensive use in pumping out sumps, shafts, and pits, and generally in handling a great variety of slurries, sludges, and waste-laden liquids. Pneumatically-driven diaphragm pumps offer certain further advantages in convenience, effectiveness, portability, and safety. In pumps of this type, the cylindrical casing of the pump is normally mounted in a substantially horizontal position, the diaphragms are disposed vertically, the connecting rod between them moves back and forth in a substantially horizontal direction, both diaphragms communicate with intake and discharge ports, and the air exhaust line vents to atmosphere. Double-diaphragm pumps are rugged and compact and, to gain maximum flexibility, are often served by a single intake line and deliver liquid through a short manifold to a single discharge line.
Among the difficulties experienced with prior art pumps are the heavy construction due to the forming of the housing from castings, which require considerable machining prior to assembly. Also, the control systems, including a reversing valve and normally a pilot valve to control the reversing valve, have embodied designs that add to the cost and complexity of construction.
While most double-diaphragm pumps of the prior art are operated pneumatically, others are hydraulically operated where the circumstances are suitable. The capability for operating such pumps with other than air pressure is highly desirable, such as where suitable compressors are not available. One very simple source of operating fluid is the water obtainable from a local water utility line where the pressure head is normally between 60 and 100 feet. In many situations, the water at line pressure can be readily used and the exhausted water collected and used locally for various purposes.
The novel pump construction of the present invention satisfies many of the difficulties and unique requirements described above, and affords other features and advantages heretofore not obtainable.